"""Application configuration (pydantic-settings).

`Settings` loads from environment variables (prefix ``APP_``) and an optional
``.env`` file, falling back to the defaults below for local dev. Keep secrets
(JWT_SECRET, HMAC_PEPPER, scraper credentials, ...) in the environment / a
secret store, never in source.

The Swedish parental-leave rule values live in the nested, frozen ``LeaveRules``
model. They are domain defaults rather than routine deployment config, but are
modelled as settings so they're typed, validated, and overridable should a rule
year change (e.g. ``APP_RULES__MAX_SAVABLE_DAYS_AT_AGE_4=96``). NOTE: these are
the common-case figures — children born before 2014, multiples, and single
custody differ and should become explicit config when tackled.
"""

from typing import Literal

from pydantic import BaseModel, ConfigDict, model_validator
from pydantic_settings import BaseSettings, SettingsConfigDict

_DEV_JWT_SECRET = "dev-secret-change-in-production-min-32-chars"


class LeaveRules(BaseModel):
    """Frozen Swedish föräldrapenning rule defaults (single source of truth)."""

    model_config = ConfigDict(frozen=True)

    sjukpenning_days: int = 390  # income-based tier
    lagsta_niva_days: int = 90  # flat low-rate tier

    reserved_days_per_parent: int = 90  # non-transferable ("reserverade dagar")

    max_dubbeldagar: int = 60  # both parents, same child-day
    dubbeldagar_months_limit: int = 15  # only within the child's first 15 months

    max_savable_days_at_age_4: int = 96  # age-4 ceiling — per CHILD (pooled across parents)
    hard_expiry_age_years: int = 12

    # A couple's per-parent age-4 pooling-loss tip (see
    # `app.utils.tip_predicates.age4_pooling_loss`) only starts warning once
    # the child has turned this many years old — the first couple of years
    # are too early to usefully act on, so don't nag before then.
    age4_pooling_tip_min_child_age_years: int = 2

    sgi_protected_first_months: int = 12
    sgi_min_days_per_week_after_age_1: int = 5

    # Default reserve for preschool planning-day ("studiedagar") closures — the
    # per-child value is user-editable; this is just the seeded default.
    preschool_planning_days_per_year: int = 6

    # Swedish statutory semester entitlement (semesterlagen). Used by
    # `AllocationInputLoader` to default a vacation-year the user has not
    # entered yet — "not entered" must never be read as "zero days".
    statutory_vacation_days_per_year: int = 25

    # Semesterlagen requires at least this many vacation days to be *taken*
    # each year; only days above it may be saved (up to 5 years). An employer
    # may set a higher floor, so this is only the seeded default — the
    # per-parent value on PersonalData.min_vacation_days_per_year is what the
    # allocator actually enforces (PLANNING_ENGINE_SPEC.md §9.2).
    min_vacation_days_per_year: int = 20

    @property
    def total_days_per_child(self) -> int:
        return self.sjukpenning_days + self.lagsta_niva_days

    @property
    def days_per_parent(self) -> int:
        """Default joint-custody split: half of each tier, summed.

        Derived rather than stored so it can never desync from
        `sjukpenning_days`/`lagsta_niva_days` if a rule year changes either.
        """
        return self.sjukpenning_days // 2 + self.lagsta_niva_days // 2

    @property
    def transferable_days_per_parent(self) -> int:
        return self.days_per_parent - self.reserved_days_per_parent

    @property
    def max_savable_days_per_parent_at_age_4(self) -> int:
        """Age-4 ceiling — per PARENT, non-poolable. `max_savable_days_at_age_4`
        (96) is a per-child pool; as soon as a child has two parents, each
        parent's own savable balance is capped at half of that (48), not 96
        each (which would let a two-parent family save 192 combined). This
        applies purely based on how many parents the child has.
        `app.utils.tip_predicates.resolve_age4_savable_cap` is the single
        place that decides which of the two applies.
        """
        return self.max_savable_days_at_age_4 // 2


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_prefix="APP_",
        env_nested_delimiter="__",
        env_file=".env",
        extra="ignore",
    )

    # Deployment environment. Gates production-only hardening (see the
    # model_validator below and main.py's docs_url handling). Never set to
    # "production" in tests/dev — the validator below will refuse to start.
    app_env: Literal["development", "test", "production"] = "development"

    # 'sqlite' for local dev, 'postgres' for production (swap repository impls).
    database_type: str = "sqlite"
    sqlite_path: str = "./foraldraledig.db"

    # Lock CORS down to the frontend origin(s).
    cors_origins: list[str] = ["http://localhost:5173"]

    # Auth — change jwt_secret in production (min 32 chars).
    jwt_secret: str = _DEV_JWT_SECRET
    jwt_algorithm: str = "HS256"
    jwt_access_token_expire_minutes: int = 15
    jwt_refresh_token_expire_days: int = 7

    log_level: str = "INFO"

    # FK scraper — legal/ToS review completed (2026-06); cleared for use.
    # Default is True. Set APP_SCRAPER_ENABLED=false to disable (e.g. an
    # environment without Playwright chromium installed).
    # Playwright chromium binaries must be installed: `playwright install chromium`.
    scraper_enabled: bool = True
    scraper_headless: bool = True
    scraper_session_ttl_seconds: int = 180  # auto-cancel awaiting_scan/authenticating sessions
    # Debug artifacts (HTML + full-page screenshot of the logged-in FK page)
    # are OFF by default — they contain personal data (name, balances,
    # payout amounts). Both fields below must be set to enable them; this is
    # a deliberate opt-in for local debugging only, never for production.
    scraper_debug_dir: str | None = None
    scraper_debug_enabled: bool = False
    # Also dump debug artifacts (HTML + full-page screenshot) after a
    # *successful* extraction, not just on error — a capture aid for
    # confirming FK's real DOM (e.g. the family panel structure assumed by
    # `app.scrapers.fk_scraper._SEL.FAMILY*`). Same personal-data warning as
    # above applies; only takes effect when both `scraper_debug_enabled` and
    # `scraper_debug_dir` are also set.
    scraper_debug_dump_on_success: bool = False
    # How long a terminal (done/error/cancelled) session's QR/result stays in
    # RAM before `_ttl_watchdog`/`poll` purge it from `_sessions`.
    scraper_result_retention_seconds: int = 300

    rules: LeaveRules = LeaveRules()

    @model_validator(mode="after")
    def _require_strong_jwt_secret_in_production(self) -> "Settings":
        if self.app_env == "production" and (
            self.jwt_secret == _DEV_JWT_SECRET or len(self.jwt_secret) < 32
        ):
            raise ValueError(
                "APP_JWT_SECRET must be set to a random value of at least 32 characters "
                "when APP_ENV=production"
            )
        return self


settings = Settings()